Rootline Navigation

Wastewater

Optimise and overcome new challenges

The wastewater infrastructure in Switzerland is worth 125 billion Swiss francs. Nine hundred treatment plants clean the country’s wastewater around the clock. Part of the work of Eawag is to examine how this success story can be continuously optimised and tailored to suit the particular conditions in other countries, as well as to look at how to overcome new challenges

News

Failed to load

The development of novel, less costly analytical methods is of crucial importance in addressing the issue of micropollutants in surface waters. This was one of the main goals of EDA-EMERGE, an EU-funded programme in which Eawag also participated. Read more

Aurin is now authorized by the Federal Office for Agriculture to be used as a fertiliser for every type of plant. Valuable nutrients from human urine are processed into high-quality liquid fertiliser — the upshot of Eawag’s “VUNA” research project. The Eawag spinoff of the same name as the project is now forging ahead with its urine recycling model. Read more

Events

Scientific publications

Review of synthetic human faeces and faecal sludge for sanitation and wastewater research

Investigations involving human faeces and faecal sludge are of great importance for urban sanitation,such as operation and maintenance of sewer systems, or implementation of faecal sludge management.However, working with real faecal matter is difficult as it not only involves working with a pathogenic,malodorous material but also individual faeces and faecal sludge samples are highly variable, making itdifficult to execute repeatable experiments. Synthetic faeces and faecal sludge can provide consistentlyreproducible substrate and alleviate these challenges. A critical literature review of simulants developedfor various wastewater and faecal sludge related research is provided. Most individual studies sought todevelop a simulant representative of specific physical, chemical, or thermal properties depending ontheir research objectives. Based on the review, a suitable simulant can be chosen and used or furtherdeveloped according to the research needs. As an example, the authors present such a modification forthe development of a simulant that can be used for investigating the motion (movement, settling andsedimentation) of faeces and their physical and biological disintegration in sewers and in on-site sanitationsystems.

Ozonation can be applied to mitigate the discharge of organic micropollutants from municipal wastewater treatment plants (WWTPs) to the aquatic environment. The toxicity of metals also present in WWTP effluents strongly depends on their speciation. Therefore, knowledge on the change of the metal speciation during ozonation of a WWTP effluent is essential to assess possible negative impacts. The kinetics and the stoichiometries of the reactions of ozone with three metal sulfides (ZnS, CuS and CdS) and metal-ethylenediaminetetraacetate (EDTA)/nitriloriacetic acid (NTA) complexes of Cu(II), Cd(II), Ni(II), Zn(II), Mg(II) and Pb(II) were investigated. With a stoichiometric factor of 2.6–3.9 moles of ozone per mole of sulfide and apparent second-order rate constants at pH 8 > 104 M−1 s−1, a complete oxidation of the sulfides and a concomitant release of the respective metals is expected during ozonation of a WWTP effluent for enhanced micropollutant abatement. The apparent second-order rate constants at pH 8 for the reactions of metal-EDTA complexes with ozone ranged from 42 M−1s−1 to 2.0 × 104 M−1s−1 and increased in the order Cd(II) < Cu(II) < Mg(II) < Ni(II) < Zn(II). Approximately 40% of Cd(II)-EDTA spiked to a WWTP effluent was oxidized at typical specific ozone doses of 0.5–0.7 gO3/gDOC. For the other metal-EDTA complexes a significantly higher fraction was oxidized. The bioavailable fraction determined by the diffusive-gradient thin films (DGT) method in the WWTP effluent increased during ozonation, due to the oxidative release of the metal ions. Algal toxicity (chlamynomodas reinhardtii) tests with CuS/CdS spiked WWTP effluent revealed a high tolerance toward Cu and Cd in the respective media. A toxic response was only observed at Cu concentrations above 10 μM, which is above typical WWTP effluent concentrations. Biological post-treatment after ozonation generally reduced the bioavailability of the metals, which resulted in a lower toxicity. Therefore, the biological post-treatment serves as an additional barrier to protect the downstream ecology of receiving waters.

Anaerobic digestion (AD) reduces the amount of waste and generates products of value, such as biogas and nutrient-rich digestate. Contrary to the wide dissemination of digesters in rural areas where animal manure is used as feedstock and despite its apparent potential, AD still plays a negligible role as a treatment option for organic kitchen and market waste in cities of low-and middle-income countries.This book compiles existing and recently generated knowledge on AD of urban biowaste at small and medium scale with special consideration given to the conditions prevailing in developing countries. Written for actors working in the waste and renewable energy sector, the book is divided into two parts: Part 1 focuses on practical information related to the AD supply chain (substrate-, process-, and product chain), and Part 2 presents selected case studies from around the world.

Most relevant research departments

Current research projects and programs

An inter- and transdisciplinary strategic research program that strives to develop novel non-gridconnected water and sani- tation systems that can function as comparable alternatives to network-based systems.